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Message-ID: <c809476f-74bc-0399-08f9-1bf26e7170fa@quicinc.com>
Date:   Mon, 24 Apr 2023 16:23:17 -0700
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Subject: Re: [PATCH v2 3/3] drm/msm/dpu: Pass catalog pointers directly from
 RM instead of IDs
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To:     Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
        Marijn Suijten <marijn.suijten@somainline.org>
CC:     Rob Clark <robdclark@gmail.com>, Sean Paul <sean@poorly.run>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        <~postmarketos/upstreaming@lists.sr.ht>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@somainline.org>,
        Konrad Dybcio <konrad.dybcio@linaro.org>,
        Martin Botka <martin.botka@somainline.org>,
        Jami Kettunen <jami.kettunen@somainline.org>,
        Jordan Crouse <jordan@cosmicpenguin.net>,
        <linux-arm-msm@vger.kernel.org>, <dri-devel@lists.freedesktop.org>,
        <freedreno@lists.freedesktop.org>, <linux-kernel@vger.kernel.org>
References: <20230418-dpu-drop-useless-for-lookup-v2-0-acb08e82ef19@somainline.org>
 <20230418-dpu-drop-useless-for-lookup-v2-3-acb08e82ef19@somainline.org>
 <50d22e0c-84b3-0678-eb06-30fb66fd24cf@quicinc.com>
 <ymq4kstme55dm3j5kr6trevnwdelhjq7e7m4yky6zcbnf7auid@66l7inxz4oq2>
 <CAA8EJprYQUFER6x1+ucHX_Ze2uqWc6xoEaYDdJ1s0jgZjPJ0QQ@mail.gmail.com>
From:   Abhinav Kumar <quic_abhinavk@quicinc.com>
In-Reply-To: <CAA8EJprYQUFER6x1+ucHX_Ze2uqWc6xoEaYDdJ1s0jgZjPJ0QQ@mail.gmail.com>
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On 4/24/2023 3:54 PM, Dmitry Baryshkov wrote:
> On Tue, 25 Apr 2023 at 01:03, Marijn Suijten
> <marijn.suijten@somainline.org> wrote:
>>
>> On 2023-04-21 16:25:15, Abhinav Kumar wrote:
>>>
>>>
>>> On 4/21/2023 1:53 PM, Marijn Suijten wrote:
>>>> The Resource Manager already iterates over all available blocks from the
>>>> catalog, only to pass their ID to a dpu_hw_xxx_init() function which
>>>> uses an _xxx_offset() helper to search for and find the exact same
>>>> catalog pointer again to initialize the block with, fallible error
>>>> handling and all.
>>>>
>>>> Instead, pass const pointers to the catalog entries directly to these
>>>> _init functions and drop the for loops entirely, saving on both
>>>> readability complexity and unnecessary cycles at boot.
>>>>
>>>> Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
>>>> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
>>>
>>> Overall, a nice cleanup!
>>>
>>> One comment below.
>>>
>>>> ---
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.c        | 37 +++++----------------
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_ctl.h        | 14 ++++----
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c        | 32 +++---------------
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.h        | 11 +++----
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dspp.c       | 38 ++++-----------------
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dspp.h       | 12 +++----
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.h |  2 +-
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c       | 40 ++++++-----------------
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h       | 12 +++----
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_lm.c         | 38 ++++-----------------
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_lm.h         | 10 +++---
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_merge3d.c    | 33 +++----------------
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_merge3d.h    | 14 ++++----
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.c   | 33 +++----------------
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_pingpong.h   | 14 ++++----
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.c       | 39 ++++------------------
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.h       | 12 +++----
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_vbif.c       | 33 +++----------------
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_vbif.h       | 11 +++----
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_wb.c         | 33 ++++---------------
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_wb.h         | 11 +++----
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c           | 17 +++++-----
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c            | 18 +++++-----
>>>>    23 files changed, 139 insertions(+), 375 deletions(-)
>>>>
>>>
>>> <snipped>
>>>
>>>> -struct dpu_hw_intf *dpu_hw_intf_init(enum dpu_intf idx,
>>>> -           void __iomem *addr,
>>>> -           const struct dpu_mdss_cfg *m)
>>>> +struct dpu_hw_intf *dpu_hw_intf_init(const struct dpu_intf_cfg *cfg,
>>>> +           void __iomem *addr)
>>>>    {
>>>>      struct dpu_hw_intf *c;
>>>> -   const struct dpu_intf_cfg *cfg;
>>>> +
>>>> +   if (cfg->type == INTF_NONE) {
>>>> +           pr_err("Cannot create interface hw object for INTF_NONE type\n");
>>>> +           return ERR_PTR(-EINVAL);
>>>> +   }
>>>
>>> The caller of dpu_hw_intf_init which is the RM already has protection
>>> for INTF_NONE, see below
>>>
>>>           for (i = 0; i < cat->intf_count; i++) {
>>>                   struct dpu_hw_intf *hw;
>>>                   const struct dpu_intf_cfg *intf = &cat->intf[i];
>>>
>>>                   if (intf->type == INTF_NONE) {
>>>                           DPU_DEBUG("skip intf %d with type none\n", i);
>>>                           continue;
>>>                   }
>>>                   if (intf->id < INTF_0 || intf->id >= INTF_MAX) {
>>>                           DPU_ERROR("skip intf %d with invalid id\n",
>>> intf->id);
>>>                           continue;
>>>                   }
>>>                   hw = dpu_hw_intf_init(intf->id, mmio, cat);
>>>
>>> So this part can be dropped.
>>
>> I mainly intended to keep original validation where _intf_offset would
>> skip INTF_NONE, and error out.  RM init is hence expected to filter out
>> INTF_NONE instead of running into that `-EINVAL`, which I maintained
>> here.
>>
>> If you think there won't be another caller of dpu_hw_intf_init, and that
>> such validation is hence excessive, I can remove it in a followup v3.
> 
> I'd prefer to see the checks at dpu_rm to be dropped.
> dpu_hw_intf_init() (and other dpu_hw_foo_init() functions) should be
> self-contained. If they can not init HW block (e.g. because the index
> is out of the boundaries), they should return an error.
> 

They already do that today because even without this it will call into 
_intf_offset() and that will bail out for INTF_NONE.

I feel this is a duplicated check because the caller with the loop needs 
to validate the index before passing it to dpu_hw_intf_init() otherwise 
the loop will get broken at the first return of the error and rest of 
the blocks will also not be initialized.


>>
>> - Marijn
>>
>>>>      c = kzalloc(sizeof(*c), GFP_KERNEL);
>>>>      if (!c)
>>>>              return ERR_PTR(-ENOMEM);
>>>>
>>>> -   cfg = _intf_offset(idx, m, addr, &c->hw);
>>>> -   if (IS_ERR_OR_NULL(cfg)) {
>>>> -           kfree(c);
>>>> -           pr_err("failed to create dpu_hw_intf %d\n", idx);
>>>> -           return ERR_PTR(-EINVAL);
>>>> -   }
>>>> +   c->hw.blk_addr = addr + cfg->base;
>>>> +   c->hw.log_mask = DPU_DBG_MASK_INTF;
>>>>
>>>
>>> <snipped>
> 
> 
>